Simian foamy viruses (SFV) are complex retrovirus that are found in all nonhuman primates (NHP) examined to date. SFV from Old World monkeys and apes has been found to be zoonotically transmitted to humans, probably through saliva. Although SFV is apparently non pathogenic in natural NHP hosts, insufficient numbers of SFV infected humans have been identified and analyzed to definitely know the effects, if any, of SFV infection. In the case of lentiviruses, also complex retroviruses, infection of natural hosts is not pathogenic, but recombination has led to HIV-1, highly pathogenic in humans. There are no publications dealing with the presence of recombinant SFV in NHP or humans. Thus far, there does not appear to be any pathology associated with Old World NHP SFV infection of humans. There have been no studies of humans infected with New World NHP SFV. We have obtained samples from American primatologists attending the American Society of Primatologists meeting. These individuals have been exposed to a large number of Old and New World NHP native to different locations, and exposure often includes bites and other primate behaviors leading to saliva transfer. Preliminary data, based only on serological analysis, suggest that an unusually large proportion of these individuals are infected with New World NHP SFV. Experiments in this proposal will confirm that these individuals are indeed infected with New World SFV, search for recombinant viruses in individuals infected with more than one SFV genotype, and follow up to examine SFV infection of humans over time. The primary techniques will be PCR and RT-PCR using specific primers in gag and pol, and isolation of SFV from human samples using susceptible tissue culture cells. These studies will greatly increase knowledge of zoonotic infection of humans by simian foamy viruses.